Stentrode

The Stentrode is a radically new approach in the field of "brain-machine interfaces" - technology that delivers mind-control over computers, robotic limbs or exoskeletons and gives people with paralysis the chance for more independence, all using the power of thought.

TRANSCRIPT

NARRATIONAnd Dr Tom Oxley, an Australian neurologist in New York, has managed to snare a cab. But he’s got a lot more to be proud of than that. He’s also grabbed the attention of the President.

President Barack ObamaThe US and Australia are funding research into a device that could some day allow people to control their prosthetics with their minds, and without invasive brain surgery.

NARRATIONIt’s called the stentrode. A radical new device designed to turn thoughts into robotic actions for people who are paralysed.

Mark TongaI could be getting up on a robotic frame and walking around.

Dr Tom OxleyThe stentrode is an endovascular brain machine interface. It is an electrode array built onto a self-expanding metal scaffold which is implanted into a blood vessel in the brain.

President Barack ObamaWhen implanted into a blood vessel, this network of tiny electrodes can record your brain’s signals.

Dr Tom OxleyWe can feed that signal into an electronic device, such as a mouse on a computer screen or any type of robotic arm. And ultimately we’d like to apply that to an exoskeleton.

President Barack ObamaTechnology that has the potential to transform the lives of our wounded warriors and others with disabilities.

NARRATIONThis is the story of a new technology that aspires to nothing less than helping paralysed people walk again. It all started five years ago when Tom pitched the concept to DARPA. That’s a US defence agency with a history of supporting high-tech ideas, including brain machine interfaces.

Dr Tom OxleyDARPA basically told me, “That’s a good idea. No-one in the group is currently trying to put an electrode up the blood vessels. We’ll give you $1 million to do that.” On the spot. And he said, “You have to go home and find a team to do that.”

Prof Terence O’BrienI like doing things that no-one else has done before and that people say can’t be done. You do the scoring?

NARRATIONProfessor Terence O’Brien helped put together the Australian team whose job it was to turn the idea into reality.

Prof Terence O’BrienWith Tom’s idea of electrodes within a blood vessel, you needed to have people who could actually make the device, but also people who knew how to deliver devices into blood vessels and people who knew about how to actually interpret the recorded information, the physiological information.

Prof Terence O’BrienAnd you also needed people who actually had experience with using animal models of neurological diseases. And so that’s at least four or five completely different disciplines that were going to be required to make this work.

Prof Clive MayNobody had any idea it would work. And that is, you know, the excitement of science – you’re trying something new that’s never been tried before.

NARRATIONThey began with the engineering challenge of designing an intricate web of electrodes, wires and scaffold that could collapse into the one-millimetre catheter they’d use to deploy it.

Dr Nicholas OpieIt’s a nickel titanium alloy that enables the metal to have shape-memory properties and super elasticity which allows it to be bent and crimped without fatigue.

NARRATIONThey also had to develop a new catheter system to reach the target area.

Prof Peter MitchellWe are going both further than we’ve gone before and through a more torturous route than we’ve gone before. You’ve gotta have something that’s pushable. So if you can’t push something, you never get around these really tight corners. And some of the tight corners are within bone, so they’re very tight to get around. So you’ve got to have a solid system at that point. But at the important end, right up close to the small veins, you have to have something extraordinarily soft and yet able to navigate, to be turned around corners.

Dr Nicholas OpieWhat we’ve had to do is combine numerous different-sized catheters to enable us to take the sharp turns and bends.

NARRATIONThe only way to test their system was in a pre-clinical trial involving sheep. They hoped their results would answer their biggest questions.

Dr Nicholas OpieCould we even get a device through the blood stream, through the blood vessels, into the part of the brain responsible for movement? So that was unknown.

Prof Clive MayWould it be able to record a signal through the blood vessel wall?

Prof Terence O’BrienWould those recordings be able to record over a long period of time and wouldn’t deteriorate with time?

Prof Clive MayAnd when we’ve got a device there, would it be safe?

NARRATIONNow, using thoughts to command computers and bionic limbs isn’t new. Indeed, human trials have been carried out for more than a decade, with impressive results. Mark Tonga became quadriplegic following a rugby injury in 2008. For him, modern technology provides access to the world today and a dream for the future.

Mark TongaI’ve always said, if you had to be injured with a severe physical impairment, like myself, this would be probably the time to be...to sustain an injury.

NARRATIONWe’ve seen people like Mark, who are paralysed from the neck down, hand themselves a beer for the first time in 13 years.

WomanAlright.

Mark TongaScull it, mate. Scull it.

WomanYay!

Mark TongaI’m not a drinker, by the way. So I wouldn’t... Wouldn’t resonate with me.

NARRATIONOr grab a big bite of chocolate.

ManIt worked!

Mark TongaHey! She got excited and the arm just jumped up.

NARRATIONAnd even reach out to a loved one.

WomanBaby.

Tim HemmesReaching out and touching my girlfriend for the first time. Holding her hand. That was...that was my highlight.

Mark TongaBrings a smile to my face. ‘Cause just the flexibility and the freedom. And I can relate to that guy ‘cause it’s a sense of achievement and being able to, you know, do something for yourself. Just...just brings me close to tears, I guess. Because it’s... You know, we’re edging closer to a person like me clawing back some sort of freedom.

NARRATIONIt’s not possible to get these results using electrodes that sit outside the skull. They’re just too far away from the neural activity. The best results are being achieved by arrays of needle-like electrodes that penetrate the brain tissue. They’ve delivered dexterity like this. Up to 10 degrees of freedom. But they don’t tend to last.

Prof Clive MayThe problem with these devices is although you get very good signals to start with, the brain sees these little needles as a foreign object. Scar tissue forms around these and the signal slowly disappears.

NARRATIONNon-penetrating arrays of electrodes have also achieved good results. They’re laid out either above or below the membrane that surrounds the brain – the dura. The team’s aim is to build on the success of these implanted devices. But with a key difference.

Prof Clive MayCurrent devices require craniotomy, which means major surgery. Cutting part of the skull out.

Prof Peter MitchellThere are so many risks associated with craniotomy. It’s such a major procedure compared to what we’re talking about here.

Dr Tom OxleySo our idea has been to avoid the need for open brain surgery by using the blood vessels to get into the areas of the brain that are information-rich in terms of motor processing.

ManAlright!

Tim HemmesThere you go.

NARRATIONWhen a person initiates a movement - or even imagines it, in the case of paralysis - multiple areas of the brain act together.

Dr Nicholas OpieThe way I like to think about neural signals and recording neural signals is to think of a football game where not much is going on. There’s a hum around the crowd but when someone kicks a goal, the whole crowd erupts. All the crowd synchronises and is yelling and shouting the same thing. In a similar way, when you’re thinking about performing an action, your brain synchronises and all the neurons align and send out a big signal that can be recorded.

NARRATIONBut each electrode can only eavesdrop on the electric field generated by a few thousand of these neurons. So the preferred place to listen in is the motor cortex.

Prof David GraydenSo there’s a region that will control the foot. A region that will control the knee, the leg, the hands and so on. And so when a person wants to do something, this area sort of coordinates that activity.

Dr Tom OxleyIt just happens that there is a very large vein running right along the top of the motor cortex. So we think the venous system provides us with a natural avenue to achieve recordings very close to the motor cortex.

NARRATIONBut making use of that natural pathway into the brain needed to be first tested in animals. So, 20 able-bodied sheep were implanted with a stentrode. The quality of the signal recorded from their motor cortices was then analysed for over six months. What they found was the stentrode embedded itself into the blood vessel wall.

Prof Clive MayIt’s possible just to see these little black dots, which represent the electrodes on the stentrode.

NARRATIONAnd there was no evidence of blood clotting, that could cause a stroke. That is a risk when traditional stents are implanted to open up blood vessels.

Prof Clive MayIt’s the result we obviously wanted. It’s very exciting because it means that these devices could be put into patients. And one would hope the reaction would be similar in patients, which means they could be left there permanently without causing any risk of blockage of blood flow.

NARRATIONBecoming embedded also brought the electrodes closer to the neurons, improving signal quality.

Prof Clive MayThe big white bright spot here is one of the electrodes. And you can see, it’s very close to the grey matter. So it really does move quite close to the brain.

NARRATIONIn fact, the quality of the signal was comparable to non-penetrating electrode arrays implanted through the skull.

Prof Terence O’BrienTo actually take the next step and show you can use that, in reality, to move bionic limbs requires the human trial.

NARRATIONAnd that’s scheduled for 2017. In the trial, Professor Peter Mitchell will implant stentrodes into three quadriplegic patients who are yet to be chosen.

Prof Peter MitchellWe have both the experimental work that’s being done and some models that are similar to this to tell us we should be able to get away with it. But it is very new.

NARRATIONTom and Nick are currently commercialising the device.

Dr Tom OxleyI’m just going to sit the catheter just beyond the origin of the internal carotid.

NARRATIONTom is at Mount Sinai hospital in New York, learning the surgical skills required.

Dr Tom OxleyDon’t move. Don’t swallow. Keep very still. Great job.

Dr J MoccoTom, I think these pictures are outstanding.

NARRATIONHe’s supervised by Dr J Mocco, a world leader in the field of neuro-intervention.

Dr J MoccoTheir basic fundamental work of being able to put this device in real-life large veins in the brain and record brain activity – once they’ve done that and shown that can happen, now after that, it’s just mechanics, it’s engineering. All they... We already have devices that know how to translate those signals. We already have proof that people can control computers or robotic arms with thought if they’re trained appropriately. And we already have devices to do that. All they gotta do now is put those pieces together. So I’m pretty optimistic.

Dr Tom OxleyMy hope for the technology is that we can help patients take some control back in their environment. That would be an amazing outcome for our team and for the patients we’re trying to come up with a solution for.

NARRATIONMark Tonga could be forgiven for being sceptical. After all, Catalyst first met him six years ago in a story on the promise of mind-controlled wheelchairs.

PresenterMy brain signals are directing the wheelchair around the room.

NARRATIONBut he remains positive.

Mark TongaHey, Sean! How are you, mate? I think one of the things I’ve developed, having an injury like this, is a lot of patience. And a lot of thankfulness that I’m alive and any little thing that technology can give me to make my life accessible would be welcome. It would be welcome.